He said: "These offences are very serious and no one has been charged in connection with them. We also need to eliminate this man from our enquiries and ascertain whether these offences are linked to Madeleine's disappearance.

"If you have been a victim of a similar crime please come forward even if you reported the incident to police in Portugal, or anywhere else, please do not assume we have been made aware of it.

"While some of these offences have been in the public domain before, following our appeal in October three more were reported to us as a direct result of that appeal. One of those reports we believe is the first in the potential series."

An appeal last year asking for information gained over 5,000 calls which created new leads for police to investigate.

Police are now calling on anyone who may know the identity of the man to come forward.

A TV appeal last year resulted in more than 5,000 calls with further evidence [GETTY]

DCI Redwood continued: "We still need to establish the identity of a man seen by three witnesses, carrying a child fitting Madeleine's description towards the beach or town areas at about 22.00 on the night Madeleine disappeared.

"The witnesses have described the man in the e-fits as being white, aged in his 30s, with short brown hair, of medium build, medium height and clean shaven."

"The Metropolitan Police Service continues to offer a reward of up to £20,000 for information leading to the identification, arrest and prosecution of the person(s) responsible for the abduction of Madeleine McCann from Praia da Luz, Portugal on 3 May 2007.

"Please call us on 0800 0961011 if you are within the UK. The number for non-UK residents is +44 207 1580 126.

"Alternatively if you do not want to speak to us directly you can contact Crimestoppers anonymously on 0800 555 111."